Change patterns of Ca related genes under various Ca levels
To illustrate the expression changes of Ca-related genes in P. massoniana seedlings under various Ca treatments, a qRT-PCR analysis was performed for the selected eight genes (Figure 6). Among these genes, except for GDH2 and RbohA , the other six genes (Figure 6A-F) are Ca receptor or Ca binding related genes in plant, and involve in Ca mediated signal transduction pathways or Ca ion homeostasis in plant. Both GDH2 and RbohA (Figure 6G and H) are plant redox processes related genes, which can be activated and regulated by Ca ions. As the result shown in Figure 6, Ca deficiency resulted in the down regulation of these genes, implying potential distributed Ca mediated various signal transduction pathways and Ca homeostasis, and impaired redox balance in P. massonianaseedlings under insufficient Ca supply condition. However, high Ca treatment recovered their expression to various extents, such asCRT3 and RbohA recovered similar expression abundance with the control (Medium Ca level) and the others even showed dramatically increased abundance compared with the control. These phenomena suggested sufficient exogenous Ca provision may promote various Ca involved signal transductions, recover Ca ion homeostasis and redox balance in P. massoniana seedlings.